A person sometimes wants to have a curved shape on furniture or partition walls. For example, in furniture, a person wants to have a human friendly shape in which the chair seat is fitted to the both wants to change the seat shape freely to accommodate the sitting posture. In partition walls, a person wants to have a curved shape, not a flat shape, to reduce acoustic reflections, or for a design friendly to young children and old people (to protect them from injuries from the unexpected wall impact).
Wall hoards made of plywood or plaster hoards cannot have curved surfaces. For this reason, board panels have been bent to provide curved surfaces. Nevertheless, to create a desired shape by bending board panel craftsmanship was required.
In order to solve the problem, Patent Document 1 discloses a board panel on which a curved surface can be formed easily by installing in that go through the board panel in the side direction on the front and back side surfaces of the board panel both made from a foamed resin, and placing the tips of the front side-slit and the back side-slit more toward the inner part than the center of the board thickness.
However, the board panel disclosed in Patent Document 1 had the following problems: (1) The board panel material is limited only to a foamed resin which provides insufficient strength by itself alone as a construction structure when pressed from the outside; therefore, bent veneers and so on also need to be laminated. (2) Doing so requires much expense in time and effort and craftsmanship. Since the lamination is performed by fixing the outside with bent veneers, the board panel cannot be removed, which is uneconomical, (3) Since slits go through the board panel in the side direction of the board panel, the surface part is a divided rectangle; therefore, even if the front face is made of a hard material such as wood and so on, enough strength cannot be obtained. Patent Document 1: Unexamined Patent Application Publication No 2009-041302.